Describe the bug

Windows builds currently show this annotation on the Actions tab:

windows-latest workflows will use windows-2022 soon. For more details, see actions/runner-images#4856

Also see github/codeql-action#850
@ann0see tried building with windows-2022 explicitly and it failed in CodeQL:
https://github.com/ann0see/jamulus/runs/4858827768?check_suite_focus=true

Error: Tracing builds with CodeQL is currently not supported on Windows 11 and Windows Server 2022. Please modify your Actions workflow to use an earlier version of Windows for this job, for example by setting runs-on: windows-2019.

We should therefore pin to windows-2019 for now.

• Pin to windows-2019
• Leave this ticket open as a reminder to switch to windows-2022 once CodeQL is fixed and no other stuff breaks (or find another way to remind us)